RGB desktop clock

[Mark Roy] designed this fine RGB LED desktop clock. It uses a PIC16F877A microcontroller and a DS1307N Real Time Clock. There is a ring of 12 RGB LEDs around the perimeter. Hours are indicated in red, minutes green, and seconds blue. If the hands overlap, the colors are mixed. Three buttons are used to set the time and it can run on as little as 0.7volts. You can find out more about the project on Stellar Core. He has plans to kit it in the future.

The clock uses a max1675 switching mode power supply that is cabable of boosting the voltage from 0.7V to 5V (or 3.3V).

The converter works by essentially charging an inductor and when it discharges, the voltage is dependant on the rate of change of current and not the input voltage, thus allowing for output voltages that differ from the input. Check wikipedia’s entry on boost converters for more details.

Some people have mentioned the issue with the going to sleep periodically.

I’d like to mention that I was thinking a solution to this would be to add a power jack or USB cable to allow the clock to be powered continuously. The beuty of the power supply is that you can give it upto 5V without any problems.